Means for polishing multifocal lenses



C GREEN.

MEANS FOR POLISHING MULTIFOCAL LENSES.

APPLICATION FILED MAR. 22, 1920.

1,372,747., Patented; M1229, 1921,

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A TTORNEYS C. GREEN.

MEANS FOR POLISHINIHMULTIFOCAL LENSES.

APPLICATION FILEED MAR-22,1920.

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CHARLES GREEN, OF INDIANAPOLIS, INDIANA, ASSIG-NOR T0 ONEPIECE BIFOCAL LENS COMPANY, OF INDIANAPOLIS, INDIANA, A CORPORATION.

MEANS FOR POLISHING MULTIFOCAL LENSES.

Specification of Letters Patent.

Patented Mar. 29, 1921..

Application filed March 22, 1920. Serial No. 367,678.

To all whom it may concern:

Be it known that 1, CHARLES GREEN, a citizen of the United States, and a resident of Indianapolis, county of Marion, and State of Indiana, have invented a certain new and useful Means for Polishing Multifocal Lenses; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, in which like numerals refer to like parts.

The object of this invention is the improvement in the means for polishing the surfaces of bifocal lenses Or other lenses hav ing a plurality of concentric surfaces, and it relates particularly to means for slmulaneously polishing said plurality of surfaces by the use of a polishing button for each surface. 1

The chief feature of the invention consists in means fo causing the rotation of the polishing buttons. The lens holder is rotated and a band of rubber or like material is placed around the lens holder and the lens or lens blank secured thereon so as to extend higher than the lens blank and form an upwardly-extending rim which engages the outer polishing button and causes it to rotate and the engaging surface thereof to travel in the same direction as the lens holder and lens. Combined with the foregoing is a belt connecting the two buttons so that the rotary movement imparted to one of them will be imparted to the other.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims.

In the drawings, Figure l is a side elevation of a portion of a lens polishing machine including this invention. Fig. 2 a 1g. 3 is a vertical sectional view through parts of the machine showing the lens blank and holder in central vertical section, the remaining parts being in front elevation and partially broken away. Fig. 4 1s a plan View of the lens, polishers and means for rotating the same that is shown in the other figures, the pin-carrying means and other mechanism being not shown. Fig. 5 is the same as Fig. 4 illustrating a modified form where only the oute polisher is driven.

There is shown in Figs. 1 and 2 parts of a machine in connection with which this invention has been and can be used, although most parts of the machine are old. There is shown a table 10 with a vertical shaft 11 mounted in the bearings 12, said shaft carrying a removable lens holder 13 of common type on which a target lens blank 14 is secured Ior treatment. The shaft 11 is driven by means of a pulley 15 and belt 16. On said tablethere is a base plate 110 carrying stationary bearing posts 17 carrying bearlngs 18 in which bearing screws 19 are horizontally mounted, as shown in Fig. 2, in connection with which the arm or frame 20 is pivoted at its rear end and its front end is acted upon by gravity for exerting pressure on the polishing means or buttons. The gravity can be increased by adding additional weights, not shown, as is often done in the practice.

In Fig. 3 there is shown a front elevation of the front end of the arm 20 which has a segmental-shaped plate 24 rigid therewith. The clamplng plate 25 is associated with the plate 24 for clamping a rod 26 in proper pos t on. Bolts 27 secure the plate 25 in position and one of those bolts extends through a slot 28 in the plate 24 so that the angular position of the clamping plate 25 may be ad usted in order to hold the rod 26 1n proper inclination.

The bifocal lens blank It as shown in Fig. 3 is secured on the lens holder 13 and as a central area 30, which is the reading surface of the lens blank, and the surrounding annular area 31, which is the distance sur face of the lens blank. These two surfaces appear in F 1g. 4, and are there shown separated by a division line 32, although in the actual lens said division line is practically invisible. For polishing the central or reading surface 30 a small button 35 is used and for polishing, the surrounding surface 31 a larger button 36 is used. The small button has a diameter equal to one-half of the diameter of the readlng surface 30 and the large polishing button has a diameter equal to the width of the distance surface 31 between the edge of the blank and the reading surface. Said blank is what is known in the trade as a target lens bifocal blank. Said two surfaces have been generated to give them the proper relative curvatures, prior to the polishing operation by the means herein set forth.

The lens holder and lens are rotated and the polishing buttons 35 and 36 are held in place by pins 37 and 38, respectively, ar-

revolution of the buttons to cause the desired cross rubbing, as the buttons will rotate almost at the speed of the lens blank at its line of contact with the polishing but ton farthest from the center of the lens blank.

The pins 37 and 38 are secured in a bar 40 pivoted by a pin 41 to the lower end of the rod 26. This enables the bar 40 to rock and permit the polishing buttons to fully engage and accommodate themselves to the surfaces of the blank during the polishing operation, and'the weight of the arm 20, rod 26, bar 10 and pins 37 and 38 will be constantly exerted on the polishing buttons in order to cause the friction desired for the polishing action.

In order to cause an equivalent polishing action by the two buttons, the bar I0 is pro- .vided with a number of holes 42 so that it can be'properly pivoted to effect said result. To this end the bearing pin l1 should be located at a point near the pin 38 of the larger button, for since the large button has two or three times the polishing surface of the small button, there should come to it through the pin 38 proportionately more pressure. Therefore, the distances between the pivot a1 and the pins 37 and 38 should be substantially in reverse ratio to the diameters of the buttons. I

Since the relative distances oftravel on the lens blank of the outer and inner edges of the large button 36 are not relatively great, the outer portion of said button does not always rotate with the'blank in the direction of the arrow and it is desirable for that button to always rotate to effect cross polishing; Therefore, the two buttons are connected by a belt 50 in grooves 51 so that the small button will always cause the large button to rotate. Since the glass blank under the outer edge of the small button travels infinitely faster than the portion under the inner edge of the small button, which is at the center of the lens blank, the lens blank always causes the outer portion of the inner button to rotate in the same direction as the blank. I

In order to positively rotate said large and outer polishing button, an elastic band 52, made preferably of rubber or the like, is stretched around the periphery of the lens holder and so as to extend above the lens or lens blank and leave a portion or flange extending above the lens or blank, as shown in Fig. 3. The outer polishing button 36 frictionally engages the inner surfaceof said rubber band and said band thereby causes positive rotation of the outer button 36, in the same direction as therotation of the-lens and lens holder. The rotary movement imparted thereby to the outer button 36 is imparted also to the inner button 35 by reason of the belt 50.

In the modified form shown in Fig. 5, the belt 50 is omitted so that although the outer button 36 is rotated positively by the rubber band in the direction of the rotation of the lens holder, no rotary movement is imparted from the outer button to the inner button 35. Hence, the rotary movement of the inner button is due solely to the action thereon of the lens during its rotation, as above explained. This construction is a satisfactory one because the inner button receives considerable rotary movement from the rotary lens and such movement is reasonably constant and uniform.

One advantage of the above construction is that the outer polishing button is given a relatively rapid rotary movement as compared with the inner button 35 and this tends to cause a more uniform action of the two polishing buttons on the lens. The outer button rotates relatively fast, as its periphery travels as fast as the periphery of the lens holder, and thus said button is enabled to polish rapidly the relatively large area of the annular surface which it treats.

The invention claimed is:

1. Means for simultaneously polishing a plurality of concentric surfaces of a lens, including a lens holder, means for rotating the same, a polishing button for each sur, face of the lens, means for holding the buttons in proper position on the lens and permitting rotation of the buttons, the outer polishing button being arranged to extend substantially to the periphery of the lens holder, and means surrounding the periphery of the lens holder and revolved thereby which frictionally engages the periphery of the outer polishing button and causes the rotation thereof.

2. Means for simultaneously polishing a plurality of concentric surfaces of a lens, including a lens holder, means for rotating the same, a polishing button for each surface of the lens, means for holding the buttons in proper position on the lens and per mitting rotationof the buttons, the outer polishing button being arranged to extend substantially to-the periphery of the lens holder and lens which may be secured thereon, and an elastic band fitting on and around the periphery of the lens holder and extending beyond the lens when secured on said holder and into frictional engagement with the outer polishing button so as to rotate the same as the lens holder rotates.

3. Means for simultaneously polishing a plurality of concentric surfaces of a lens, including a lens holder, means for rotating the same, a polishing button for each surface of the lens, means for holding the buttons in proper position on the lens and permitting rotation of the buttons, the outer polishing button being arranged to extend substantially to the periphery of the lens holder and lens which may be secured thereon, means surrounding the periphery of the lens holder and revolved thereby which frictionally engages the periphery of the outer polishing button and causes the rotation thereof, and' a belt surrounding the polishing buttons for transmitting rotary movement from one to the other.

4. Means for simultaneously polishing a plurality of concentric surfaces of a lens, including a lens holder, means for rotating the same, a polishing button for each surface of the lens, means for holding the buttons in proper position on the lens and permitting rotation of the buttons, the outer polishing button being arranged to extend substantially to the periphery of the lens holder and lens which may be secured thereon, an elastic band fitting on and around the periphery of the lens holder and extending beyond the lens when secured on said holder and into frictional engagement with the outer polishing button so as to rotate the same as the lens holder rotates, and a belt surrounding the polishing buttons for transmitting rotary movement from one to the other.

In witness whereof, I have hereunto afEXed my signature.

CHARLES GREEN. 

